I have built a 32 bit application on Mac and I do not have enough time to migrate that to 64 bit. Is there any way using SheepShaver or any other product, I will still be able to run 32 bit applications post High Sierra timeframe?

Compiling an application against the 32-bit Cocoa x86 framework means it will run in OS X 10.4 Intel through OS X 10.13 Intel -- assuming you compiled against the 10.4 development framework.

So the first question is: what architecture did you build your app for? Which OS does it target?

Using VirtualBox, Parallels Desktop Lite or VMWare Fusion, you can install OS X 10.6 through 10.13 in a virtual machine. I keep a 10.6 VM around for running Adobe CS4, an XCode development environment that can compile 10.4PPC through 10.6Intel, and a few other things. Such an image would also likely run your software as long as it was at least compiled for 32-bit PPC and Carbon-ready.

The latest XCode has a number of utilities to aid in converting from 32 to 64 bit.

What I'm curious about is if we're eventually going to need a 32-bit emulator: the instruction set for 64-bit Intel is actually different than the 32-bit instruction set, so if Apple drops 32-bit instructions at the hardware level, virtualization won't cut it.

So with 10.14, we'll lose access to 32-bit APIs in the OS, but it's technically possible that we'll lose access at the chip level before too long as well.

[edit]

Code:

To enable 64-bit mode: 1. Launch Terminal 2. Execute the following command: sudo nvram boot-args="-no32exec" 3. Restart the machine 64-bit test mode prevents 32-bit processes from launching. Launching an app that depends on 32-bit software results in a notification that the application can't be opened. Other types of software may fail silently, such as 32-bit versions of Dashboard and WebKit plugins, preference panes, and background processes. Disable the test mode once the software is updated to work in 64-bit. To disable the test mode: 1. Launch Terminal 2. Execute the following command: sudo nvram boot-args=“” 3. Restart the machine